The present invention relates to a new and improved construction of apparatus for monitoring yarn travel at a multiple spindle spinning machine equipped with a suction device servicing at least one group of the spindles, a probe being arranged in a collecting channel of the suction device, this probe, upon passage therepast of fiber flocks or the like delivering an electrical signal to an evaluation circuit. The evaluation circuit contains a periodically resettable signal counter having a pre-set counter value or state, the evaluation circuit being operatively coupled with an alarm device.
Now in German Pat. No. 1,685,885, and equally in the earlier German patent publication 26 43 453 there is disclosed for instance such general construction of monitoring device. With this state-of-the-art equipment there are described special measures in order that there is infed to the evaluation circuit with the greatest probability only such signals which, in fact, are predicated only upon fiber flocks which move through the collecting channel. Fiber flocks which travel in the suction channel however, in turn, are an indicia that an irregular operating state prevails at the monitored spinning machine, for instance that there has arisen rupture of a yarn or roving. With the prior art equipment there is thus not directly detected the presence or absence of an intact yarn at the spindles. Rather, based upon the material existing within the suction device a decision is reached as to the operating state of the spinning machine. Equipment of this type therefore basically is different from other, likewise prior art equipment, for instance of the type disclosed in German Pat. No. 1,907,990 or German patent publication 22 62 425, wherein by means of stationary or migrating monitoring elements there is directly detected the presence or absence, as the case may be of intact yarn at the spindles.
With the previously mentioned prior art monitoring apparatus the periodically resettable signal counter triggers the alarm device then if during one or two successive counting periods the counter value which has been pre-set at the counter has been reached or exceeded. This pre-set counter value allows determinations to be made regarding the number of yarn ruptures which have occurred. This is so because each yarn rupture--depending upon the quality and nature of the roving or the like processed at the spinning machine and as long as the spinning machine continues to operate--serves to form a sequence of timewise successive fiber flocks which are produced due to the disintegration of the still infed roving, and the recurrence within a certain time period, i.e., so-to-speak the "frequency" of the moving flocks is within comparatively narrow limits for each yarn rupture. The greater the number of yarn ruptures which have occurred that much greater is the recurrence or frequency (per counting period) of the flocks which are moving past.
As already mentioned, with the state-of-the-art monitoring device the alarm device is then first triggered, for instance for calling an operator or for turning-off the machine, when this recurrence exceeds a predetermined value, namely the counter value set at the signal counter. The system is designed with the view of first then undertaking corrective measures during the operation of the machine if, based upon the detected number of fiber flocks which move past, there can be determined such a number of yarn ruptures that the economies of further operating the spinning machine when these conditions have arisen becomes questionable. If, however, the operator takes corrective action and eliminates the yarn rupture at the spindles which require servicing during the further operation of the spinning machine, the prior art equipment does not afford for the operator any indication as to when the servicing and corrective work has progressed to an extent such that an economical further operation of the machine can be again carried out notwithstanding possibly still uncorrected yarn ruptures or yarn ruptures which have newly arisen in the meantime.
This is especially then disdadvantageous if, as is presently oftentimes the case, a single operator is responsible for the monitoring of an entire series of spinning machines. In such case the operator is not informed that the servicing or corrective work at the one spinning machine has sufficiently been accomplished so that he can discontinue his or her efforts and proceed to pay attention to a further spinning machine where likewise there has been triggered the alarm device.
Additionally, the prior art equipment is not capable of detecting all of the operating conditions which are desirable for the operator to take corrective action. For instance if per chance a yarn rupture arises at only a few spindles, at the remaining spindles however no such yarn rupture occur, then it is quite possible that this operating state can continue for a limited period of time. Since the prior art equipment only however detects the recurrence or frequency of the flocks per counting period, the flocks which are produced by the few yarn ruptures are not even capable of attaining the recurrence threshold needed for triggering the alarm device, even if the machine remains in operation over a longer period of time.